Introduction: Wire arc additive manufacturing (WAAM) is a promising technology for producing near-net shapes of metal alloys in designs with complex geometries. EBAM requires minimal tooling and material removal required during post processing as compared to traditional manfuacturing methods. However, the microstructures that form during WAAM di er considerably from those observed in traditionally manufactured samples. In the additive manufacturing of Ti-6Al-4V several di erent microstructures have been observed. Murr et al. characterized the morphology of colonies as a function of location within a build, observing basketweave (Wdmanstatten) microstructures of acicular grains. Murr observed that the size of the grains changed with di erent deposition layers, with layers closer to the part substrate having a smaller grain size . Varying microstructure within a single build is likely to have an impact on mechanical properties of the part, such as hardness, tensile strength, and ductility. The variance in microstructure may be tracked back to the manner in which cooling occurs in melt pools of the build. The direction of heat conduction, in particular, plays a role in how solidi cation occurs.
Authors: Nathan S.D.E.F. Johnson, Branden Kappes, and Aaron P. Stebner
Keywords: additive manufacturing, Ti-6Al-4V, wire arc additive manfuacturing, synchrotron X-ray diffraction